Britain’s National Energy System Operator restricted power exports to European neighbours in July to preserve supplies during a heatwave, official data analysed by the FT shows. The state‑owned operator told wholesale market traders not to export via four of Britain’s ten interconnector cables for several hours.

The move marks the first time the official designation margin extremes was used to cut export capacity to zero on the Nemo, Viking, North Sea Link and Eleclink links connecting Britain to Belgium, Denmark, Norway and France. Summer demand for air‑conditioning and lower plant efficiency, plus drought‑driven nuclear shutdowns in Europe, have tightened the grid.

Neso’s actions on June 23, when exports to the Netherlands were abruptly halted, are under investigation by the regulator and have been raised in parliament by Claire Coutinho. The operator says the restrictions are part of its established approach to maintaining security for consumers.